1. Field of the Invention
The present invention relates to ovens for cooking food for professional use and more particularly tunnel ovens for cooking.
2. Description of the Related Art
There are known tunnel ovens comprising a generally elongated chamber in the form of a parallelepiped of a length of the order of 6 meters which is divided into a succession of cooking chambers. This enclosure is at one of its ends connected to an inlet closure and at the other to an outlet closure.
The intermediate zones between the chamber and the closures conventionally have an incurred shape, the inlet closure being connected to a loading zone, while the outlet closure is connected to a discharge zone for the foods to be cooked.
The loading and discharge zones can be connected in a common handling zone, such that the installation forms an elongated loop which comes together in this handling zone.
These tunnel ovens operate continuously and their capacity is for example about 2500 portions in 7 hours of operation at 250.degree. C., the foodstuffs being during cooking contained in trays disposed on carriages which move through the tunnel on a conveyor.
The tunnel ovens are generally provided with different and complementary heating means so as to accelerate the cooking and to ensure at the same time a good quality of the foods, both as to their nutritional value and as to their appearance.
Thus, the tunnel ovens are preferably provided for simultaneous cooking, mixed or separated in function as to the foods to be cooked, with the aid of microwaves, pulsed air, steam and infrared radiation.
These heating modes are selected as a function of the foods to be cooked and their individual specifications. Thus, microwaves permit above all obtaining the greatest rapidity of cooking, the efficacy of this mode of heating being immediate. Steam heating permits avoiding loss of weight and also permits preserving the organoleptic properties of certain products which otherwise would be changed.
The pulsed air heating conjointly with other heating modes, if desired supplemented by infrared radiation, permits preserving the typical advantages of a conventional type of oven, particularly the possibility of browning and searing the surface of certain products.
Each chamber in the series of chambers acts like an oven and is separated from the following chamber by a deflector suspended from one wall forming the ceiling of the chamber. Each chamber is generally associated with several microwave sources, each source being connected to a microwave generator by means of a waveguide and empties into the interior of the chamber through a microwave emission member in the form of a coupling iris, of an antenna or of a slotted guide.
The microwave emission members within each chamber can be disposed in a side wall of the enclosure or in the wall forming the ceiling of the latter. They are in a known tunnel oven disposed in the ceiling and aligned along a line passing through a transverse plane of the chamber. These microwave emission members should be disposed at a certain distance from each other to avoid interference phenomena, which would result in the microwave emission members not being arranged in an optimum manner relative to the trays.
Each chamber is also associated with a hot air production group comprising a turbine, shielded resistances and a deflector grill. This hot air production group is mounted to one side of the enclosure in the body of the tunnel oven and the deflector grill is integrated into a side wall of the enclosure adjacent the corresponding chamber.
The provision of steam in each chamber is ensured by means of a distribution member in the form of at least one injection nozzle which projects within the chamber and which is connected to an apparatus for steam production.
Finally, the infrared radiation producing elements are constituted by shielded resistances or any other infrared emitter which is suspended in each chamber from the wall forming the ceiling of the enclosure.